The magic behind K Flex material

How can you combine all the important properties that a clear aligner should have in just one material? A Clear Aligner should:


- exert force continuously without causing pain

- be comfortable to wear

- be invisible and staying clear while using it


It is difficult to combine all properties in one material. That's why we at K Line are one of the few aligner manufacturers in Europe to use the unique K Flex material. Dual-shell structure provides the ability to rebound

K Flex consists of a combination of high-performing materials in a dual-shell structure. The material combines an inner shell and an outer shell. The inner shell is tough and grips the teeth firmly to exert a firm and sustained force on the teeth and move them in a precisely controlled manner. The outermost shell provides abrasion resistance, acting as a tough barrier to grinding or bruxing forces of the teeth. Sandwiched between the outer and inner shells, lies the central elastomeric layer which provides elasticity to the entire structure.




The central layer prevents the aligners from getting deformed over time, which is a common disadvantage with most clear aligners, with long-term use due to repeated insertion and removal.




It provides the Clear Aligners with the ability to rebound and recover from mechanical deformation. Forces applied in any direction – including rotational forces – receive a rebound response.







K Flex vs. other thermoplastic materials



Thermoplastic materials might have strength but lack elasticity. They cannot react flexibly to a deformation.





K Flex however provides our Clear Aligners with the ability to rebound and recover from mechanical deformation.








How does this transform into a better aligner?





Thermoplastic materials enter the mouth with a higher force placed on teeth, then decline in force over time. K Flex, however, enters the patient's mouth with up to 40% less initial force.


This reduces pain for patients upon insertion of the Clear Aligners. Also, the elastic recovery provides greater tooth-moving forces over a period of time. That is not possible with standard thermoplastic materials.


A patient inserting an aligner made out of PETG, notice the high pitched sounds on insertion indicating loss of flexibility.







A patient inserting K Flex, easier aligner insertion, and higher flexibility. Notice now the change in seating and comfort after activation!





K Flex provides positive treatment outcomes which will eventually always lead to happier patients!